1. Field of the Invention
The present invention relates to a tire vulcanizer known as a vulcanizing and molding press for green tires, in which a plurality of vulcanizing molds installed on a vulcanizer frame may be individually driven and operated, wherein the construction and operation of a mold clamping mechanism and a mold height adjusting mechanism in each of the molds are simplified and facilitated.
2. Description of the Prior Art
A tire vulcanizer of the type in which a plurality of vulcanizing split molds are juxtaposed has been known, said tire vulcanizer comprising, in a common vulcanizer frame, a lower mold provided on the base frame side and an upper mold provided on the side frame side, said upper mold being vertically movably and open- and closable toward the lower mold. One example of such vulcanizer is disclosed in Japanese Unexamined Publication No. Sho 59-71842 filed by the present applicant. In this conventional vulcanizer, as shown in FIGS. 1 to 5 thereof, lower molds 14 secured onto a vulcanizer base 1 and upper molds 15 vertically movably and open- and closable toward the lower molds 14 are provided along the guides 3, 3 which are side frames stood upright on the base 1, the upper molds 15 being individually moved up and down by a plurality of fluid pressure cylinders 4 disposed correspondingly in the periphery thereof. Piston rods 17 equadistantly arranged on the vulcanizing base 1 encircling the outer peripheries of the lower molds 14 and including lock portions 18 are provided, as a clamping mechanism for both upper and lower molds, and a plurality of clamping fluid pressure cylinders 2 which makes the locking position of the lock portions 18 variable according to the height of the molds are provided. A clamping movable lock shaft 32, which is engaged with and disengaged from the lock portion 18 of a piston rod 17 of the cylinder 2, is provided in the outer periphery of the upper mold 15 and corresponding to the cylinder 2. With this, the upper mold 15 is made to be closed with respect to the lower mold 14 to cause the lock portion 18 of the piston rod 17 of the fluid pressure cylinder 2 to move into a locking leg 9 of the upper mold 15 so as to engage a lock tail 31 of a lock shaft 32 of the leg 9, and rotation of the lock shaft 32 through 90 degrees locks the lock tail 31 and the lock portion 18, whereby the piston rod 17 of the cylinder 2 is moved downward to clamp the upper and lower molds 14 and 15. If different molds are used and the mold height is then varied, the piston rod 17 of the clamping fluid pressure cylinder 2 is threadedly turned for upward and downward movement to change the position of engagement with the lock tail 31 of the lock shaft 32. An apparatus for clamping upper and lower molds generally known is of the system in which a connection end of upper and lower domes provided to encircle the outer peripheries of upper and lower molds is clamped by a breech-lock mechanism (for example, such as Japanese Patent Unexamined Publication No. Sho 59-138432 which corresponds to U.S. Pat. No. 4,563,130).
Generally, a tire vulcanizer frequently used is of a twin type in which two vulcanizing molds in the form of open- and closable upper and lower molds are juxtaposed on the vulcanizer frame. Usually, in the juxtaposed open- and closable upper molds in the vulcanizing split molds, top slides which form the upper construction of the upper molds are connected to each other by a connecting beam so that they may be opened and closed together. Paired synchronous driving operation is advantageous in view of productivity and operating efficiency but, in the event a mold different in thickness (or height) is used in either mold, such is disadvantageous in view of operation because accurate adjustment of the mold height is required. In the case of the twin type vulcanizer disclosed in Japanese Patent Application Laid-Open No. 22118/1982, each vulcanizer mold is constructed such that the upper mold is individually opened and closed by an exclusive-use elevating cylinder, and therefore, even if molds different in thickness (or height) are used, adjustment of the mold height can be easily carried out and vulcanizing of tires different in size may be facilitated. In addition, only one vulcanizing mold can be operated while the other is at rest. This system is suitable for a small production of a variety of kinds but has the following problems in clamping of the molds and the mechanism for adjustment of mold height. In the aforesaid patent, four clamping fluid pressure cylinders 2 are provided on the undersurface of the vulcanizer base encircling the outer periphery of the lower molds 14, and the piston rods 17 of the cylinders 2 are projected externally of the lower dome 14a. Similarly, four lock shafts 32 are likewise disposed encircling the outer dome 15a of the upper die 15 so that closure of the upper mold 15 with respect to the lower mold 14 is made completely, the lock portion 18 of the piston rod 17 is moved into the lock tail 31 of the lock shaft 32, and the lock shaft 32 is turned to lock the lock portion 18 and the lock tail 31, the piston rod 17 being pulled down to effect clamping. In adjustment of the mold height, the piston rod 17 in the cylinder 2 is moved up and down to vertically change the lock position. That is, the provision of four clamping lock shafts 32 around the upper mold 15 and of four piston rods 17 around the lower mold 14, in a limited space of the vulcanizer frame, is disadvantageous because the construction becomes complicated. Furthermore, there is required a moving mechanism for simultaneously driving four lock shafts 32 and a moving mechanism for simultaneously moving four piston rods 14, resulting in a further complication of the entire construction as required. In the tire vulcanizer, as is known, a thermal pressure medium such as steam is used for vulcanization and molding and therefore such is placed under high heat and high pressure environments. In clamping molds, the upper and lower molds are clamped against the thermal pressure medium supplied thereto, and therefore, apart from the upper mold and lower mold, the upper dome 15a and lower dome 14a surrounding the upper and lower molds, respectively, and the base frame and top link (top frame and top beam) are liable to receive flexure and deformation due to the clamping reaction. In addition, there is a tendency that the distribution of clamping force in the upper and lower mold is strong on both sides of the mold and is weaker than the former in the central side. The provision of the clamping mechanism and various moving mechanisms around the molds and of various moving mechanisms as described above therefore still pose problems in that various parts of the assembly are adversely affected.